Help with p0455

Kyle Grasso · February 23, 2022

Hello its been so long since ive been on here I forgot my username! Anyways I now have a 2003 Silverado 5.3 and have had more issues with this truck than all my previous GM trucks combined. Ive been chasing evap issues from the first day i got this truck over 2 years ago. Ive replaced the gas cap, vent valve, purge solenoid, and pressure sensor. That worked and kept the CEL at bay for awhile. Then I started getting a p0455 code when the fuel tank ran low only, except now it comes on anytime. After i clear the code it comes back within 30miles of driving. What should I check next? Thanks

Mr. Z71 · February 24, 2022

Maybe time to do an EVAP Smoke Test to check for leaks?

Kyle Grasso · February 24, 2022

I have visually inspected as much line and connections as possible so I guess smoke would be the next step. I have never done that before but theres a first for everything.. youtube here I come! Lol

Mr. Z71 · February 24, 2022

Here’s my experience with a P0455 on my ’03 Sierra. Fought it on and off for a couple of years with a local non-GM repair shop (am unable to do my own repair work anymore) and over the course of those couple of years they replaced the vent valve and solenoid, relocated the filter, replaced the purge valve and I had replaced the fuel cap. Each time it was fine for a while but the DTC would return eventually. I finally took it to a GM dealership and they said it had a bad tank pressure sensor and replaced it. This cured the problem… been fine for almost a year now.

After this, I looked back through my service records and found that the P0455 started setting after a fuel pump replacement. A non-GM pump with sensor was installed. This fuel pump went out a little under a year later and was replaced under warranty, again, with a non-GM pump and sensor. Once diagnosed by the GM dealership and replaced with a GM sensor the problem was fixed. I attribute the DTC to the fact that each fuel pump that was installed had a sensor that did not meet GM specs and thus, due to being out of spec, would throw the code eventually.

Are you using GM parts? This is not the first time I’ve been bitten by using non-GM parts, happened with non-GM knock sensors on the same vehicle. Kept throwing sensor faults until the shop got tired of replacing them under warranty and finally put in GM parts. Voila… issue resolved.

dna9656 · February 24, 2022

The use of non GM parts failing due to the fact they are non GM... I wonder about the legalities of that. My tranny guy recommends the use of AC Delco tranny fluid in the trannys and X fer cases ONLY. He won't cover a warranty repair if you use something else. How he knows the difference I donno...

I have read in the GM forums of guys using non GM wire harness under the Intake manifold and they don't work, I don't remember what was wrong but using the GM part there was no problem. The problem with this is most people don't want to pay the exorbitant prices at the dealer; I don't either and will resist because I'm thrifty (cheap) and yes i do realize that Dealers hire (or are supposed to be hiring) the best and brightest, train them a lot and so with people like that you go to pay a good wage to keep them. Sometimes we have to bite the bullet and pay but consider this: getting a part that works right the first time is worth how many re dos? Ask those guys that replaced the fuel pump in the above post(s). Dropping a fuel tank is a MAJOR PIA; I know; I have done it more tan a few times. I was in the military vehicle maintenance shop assigned to allied trades (aka the body shop) and we were responsible for the repair of fuel tanks and radiators, I have pulled/dropped many of each and soldering fuel tanks is not my idea of a good way to spend the afternoon. We did it with a hot iron, no flame of course, and we had to purge the tanks with exhaust fumes from a running vehicle for 2 hours minimum to get the gas outta there. Now with plastic tanks it's a different issue today but so far as I know heavy equipment still has metal fuel tanks...they still rust and need repair.s

Brenden Burnham · February 25, 2022

I was going to say replace the fuel pump with a OEM ACDelco and only ACDelco. This is one of those parts you DO NOT want to go cheap or use non OE for this exact reason. Having to change it out is a B!@TCH(fuel tank always seems to be full when the pump goes out). Just do it right and get 100k+ out of it is the way I see it.

If only they would make a fuel pump access-panel of some kind. One could only wish ugh.

Edited February 25, 2022 by Brenden Burnham

Kyle Grasso · February 25, 2022

I went through and replaced everything as well only to then find out about the pressure sensor! I replaced the entire fiel pump at that time because it still had the original pump in it and was weak. I did not use a GM pump and you guys have me worried now. I guess I will just deal with it until the pump fails. The truck is severely rusted and has many problems so its not worth putting any more money into like that. Access panel for the pump you say? I cut a nice 14"x14" access panel into the bed floor for quick and easy pump access! Lol

Mr. Z71 · February 26, 2022

Not saying this is your problem, but you can replace just the sensor, you don’t have to replace the whole pump. If you have cut an access hole, it ought to be a breeze to replace the sensor. GM part number is 16238399. This is the one my truck uses, should be the same for yours. My truck is a 2003 GMC Sierra w/5.3L gas (not Flex Fuel) engine.

Here’s a GM one on eBay …

https://www.ebay.com/itm/353759723733?hash=item525db900d5:g:HpwAAOSwLgFch6tr

dmoff46606 · March 3, 2022

If you're going to replace the pump, you can do it without dropping the tank or cutting an access hole in the bed. Here's a link to a video that shows how:

If you're going to replace only the sensor, try to find a shop/mechanic (or you) that knows how to replace the sensor without dropping the tank (the mechanic needs to have small hands). If that doesn't work, tip the bed as in the attached video.

Kyle Grasso · March 3, 2022

Unfortunately my truck is so rusted that even attemping to remove the bolts or tilt the bed would end in catastrophe! I swear the paint is holding most of it together. I think I may have finally found my issue though. Theres a rust hole in the outer ring of the gas filler. The metal part that you actually stick the gas puml nkzzle into. There seems to be an inner and outer sleeve to it so it never leaks fuel when filling up. I epoxied the hole and wrapped a piece of heavy hose around it secured with 2 hose clamps. So far no CEL! Havent driven it far though. Fingers

Kyle Grasso · March 3, 2022

Btw its a shame how rusted this body style seems to get. Ive owned multiple Chevy/GMC trucks ranging from 1989 to 1998 that were in much much better shape even with more mileage.

Brenden Burnham · March 3, 2022

12 hours ago, dmoff46606 said:

If you're going to replace the pump, you can do it without dropping the tank or cutting an access hole in the bed. Here's a link to a video that shows how:

If you're going to replace only the sensor, try to find a shop/mechanic (or you) that knows how to replace the sensor without dropping the tank (the mechanic needs to have small hands). If that doesn't work, tip the bed as in the attached video.

Not sure why they do not include an access panel from the factory in the first place. 90% of the time the fuel pump does not last the life of the truck. I guess this is one of the jobs that help keep the mechanics employed lol.